Unix timestamp converter

How to use the Unix timestamp converter

  1. Enter a Unix timestamp (seconds or milliseconds) — the converter auto-detects which.
  2. See the result in multiple formats: ISO 8601, RFC 2822, human-readable, and for every major timezone.
  3. Reverse direction: enter a human date and get the Unix timestamp.
  4. Bulk mode: paste a CSV column of timestamps to convert a whole spreadsheet column at once.

When to use it

Use Unix seconds (the classic 10-digit integer) when you're storing timestamps in a database and want compact integer comparison. Use Unix milliseconds (13-digit) when you need sub-second precision, which matches JavaScript's Date.now(). Use ISO 8601 strings (2026-04-22T19:45:00Z) in API responses and JSON — they're human-readable and unambiguous across languages.

Frequently asked questions

Why are some timestamps 10 digits and others 13?
10 digits = seconds since 1970-01-01 UTC. 13 digits = milliseconds. Both are 'Unix timestamps.' Most languages default to seconds except JavaScript, which uses milliseconds.
What's the Year 2038 problem?
32-bit signed Unix timestamps overflow on January 19, 2038. Modern systems use 64-bit integers which are good for 292 billion years. Most infrastructure migrated in 2018-2022.
How do I handle timezones?
Always store and compute in UTC. Convert to the user's local timezone only for display.
Can I convert Excel dates to Unix?
Yes — Excel's date serial (days since 1899-12-30) is handled in bulk mode. Paste the column and pick Excel as the source format.

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Last updated: 2026-04-22